Log Message:
tahoe-lafs: Update to 1.15.0

Release 1.15.0 (2020-10-13)
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Features
--------

- PyPy is now a supported platform. (`#1792 \ 
<https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1792>`_)
- allmydata.testing.web, a new module, now offers a supported Python API for \ 
testing Tahoe-LAFS web API clients. (`#3317 \ 
<https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3317>`_)

Dependency/Installation Changes
-------------------------------

- Tahoe-LAFS now supports CentOS 8 and no longer supports CentOS 7. (`#3296 \ 
<https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3296>`_)
- Tahoe-LAFS now supports Ubuntu 20.04. (`#3328 \ 
<https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3328>`_)

Removed Features
----------------

- The Magic Folder frontend has been split out into a stand-alone project.  The \ 
functionality is no longer part of Tahoe-LAFS itself.  Learn more at \ 
<https://github.com/LeastAuthority/magic-folder>. (`#3284 \ 
<https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3284>`_)
- Slackware 14.2 is no longer a Tahoe-LAFS supported platform. (`#3323 \ 
<https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3323>`_)